With the increasing efforts to reduce dependency upon petroleum based fuels, there has been a movement toward alternative energy sources. One technology that has seen increased attention in recent years has been fuel cell technology. In a typical fuel cell, electricity is derived electrochemically by reactions typically carried out with fluidic reactants and what is known in the art as a membrane electrode assembly (MEA). Typically, multiple MEAs are electrically combined in series, parallel or both to form a fuel cell stack. MEA structures will typically employ a membrane sandwiched between anode and cathode sheets. A catalyst may be included within an MEA. In turn, the MEAs are provided between current collectors in the form of plates, such as bipolar plates. Such bipolar plates may be specifically configured with one or more channel structures through which reactants are flowed, or through which reaction product flows. As can be appreciated, there is a need to isolate active components of a fuel cell. For example, the portions of the fuel cell exposed to reactants and/or other fluids and chemicals need to be isolated from the portions exposed to reaction products. As well, it is desirable to contain the system from the surrounding environment. Accordingly, the art has recognized that fuel cell stacks should be sealed. Efforts to seal components of fuel cells have been described in various prior publications, such as U.S. Pat. Nos. 7,722,978; 7,824,821 and 7,914,943.
Some fuel cells herein may be polymer electrolyte membrane type fuel cells. A polymer electrolyte membrane fuel cell may make use of an electrochemical reaction using a polymeric electrolyte. For example, an electrochemical reaction involving conversion of hydrogen and oxygen to water may involve oxidation and reduction partial reactions, and may employ a proton-conducting membrane between anode and cathode electrodes. Such fuel cells are commonly operated at a temperature in the region in excess of 50° C., and even as high as 90° C. or higher, and thereby subject materials used for the components to relatively high temperatures. As a result, over time, the potential for polymer material degradation at such temperatures tends to limit the ability to use such polymeric components, or requires that such components be used in relatively large amounts to assure robust performance.
To date, however, the ability to achieve high integrity sealing has been limited. For example, due to the demanding environments in which the fuel cells will be operated, the ability to employ a range of sealing materials has been curtailed. Further, the need to apply sealing material in sufficient thicknesses needed to achieve the desired sealing performance has compromised the ability to make fuel cells more compact and lighter in weight. In this regard, the push toward the use of thinner and more fragile sheet materials renders the use of some sealing materials impractical. Accordingly, there remains a need in the art for the improved manufacture of fuel cell stacks and sealed fuel cell assemblies, which are relatively compact, durable, relatively light in weight, and/or which can be employed with relatively thin fuel cell component materials without detrimentally affecting the performance of the component materials.